Section 5G. A city or town may establish a municipal waterways improvement and maintenance fund to receive revenue under subsection (i) of section 2 of chapter 60B and under section 10A of chapter 91 and sums received from the commonwealth or the federal government, and may appropriate monies in said fund for (1) maintenance, dredging, cleaning and improvement of harbors, inland waters and great ponds of the commonwealth, (2) the public access thereto, (3) the breakwaters, retaining walls, piers, wharves and moorings thereof, and (4) law enforcement and fire prevention.